A policy that only works for one result type, because it produces a result of its own. fallback is the only one here.
It cannot go in a stack, which is a list of policies that work for every type; it wraps the stack instead.
A policy that only works for one result type, because it produces a result of its own. fallback is the only one here.
It cannot go in a stack, which is a list of policies that work for every type; it wraps the stack instead.